Problem: Khan.scratchpad.disable(); Christopher sells magazine subscriptions and earns $$6$ for every new subscriber he signs up. Christopher also earns a $$21$ weekly bonus regardless of how many magazine subscriptions he sells. If Christopher wants to earn at least $$99$ this week, what is the minimum number of subscriptions he needs to sell?
To solve this, let's set up an expression to show how much money Christopher will make. Amount earned this week $=$ $ $ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus Since Christopher wants to make at least $$99$ this week, we can turn this into an inequality. Amount earned this week $\geq $99$ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus $\geq $99$ We are solving for the number of subscriptions sold, so let subscriptions sold be represented by the variable $x$ We can now plug in: $x \cdot $6 + $21 \geq $99$ $ x \cdot $6 \geq $99 - $21 $ $ x \cdot $6 \geq $78 $ $x \geq \dfrac{78}{6} = 13$ Christopher must sell at least 13 subscriptions this week.